Prioritize retrieval of environment variables from IConfiguration instead of directly

src/Dapr.Actors.AspNetCore/ActorsServiceCollectionExtensions.cs

@@ -1,4 +1,4 @@
-// ------------------------------------------------------------------------
+// ------------------------------------------------------------------------
 // Copyright 2021 The Dapr Authors
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -11,9 +11,13 @@
 // limitations under the License.
 // ------------------------------------------------------------------------
 
+#nullable enable
+
 using System;
+using Dapr;
 using Dapr.Actors.Client;
 using Dapr.Actors.Runtime;
+using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
@@ -30,12 +34,9 @@ public static class ActorsServiceCollectionExtensions
         /// </summary>
         /// <param name="services">The <see cref="IServiceCollection" />.</param>
         /// <param name="configure">A delegate used to configure actor options and register actor types.</param>
-        public static void AddActors(this IServiceCollection services, Action<ActorRuntimeOptions> configure)
+        public static void AddActors(this IServiceCollection? services, Action<ActorRuntimeOptions>? configure)
         {
-            if (services is null)
-            {
-                throw new ArgumentNullException(nameof(services));
-            }
+            ArgumentNullException.ThrowIfNull(services, nameof(services));
 
             // Routing and health checks are required dependencies.
             services.AddRouting();
@@ -45,6 +46,16 @@ public static void AddActors(this IServiceCollection services, Action<ActorRunti
             services.TryAddSingleton<ActorRuntime>(s =>
             {   
                 var options = s.GetRequiredService<IOptions<ActorRuntimeOptions>>().Value;
+
+                //Replace the HttpEndpoint with an endpoint prioritizing IConfiguration
+                var configuration = s.GetService<IConfiguration>();
+                options.HttpEndpoint = options.HttpEndpoint != "http://127.0.0.1:3500"
+                    ? GetHttpEndpoint(configuration)
+                    : options.HttpEndpoint;
+                options.DaprApiToken = string.IsNullOrWhiteSpace(options.DaprApiToken)
+                    ? GetApiToken(configuration)
+                    : options.DaprApiToken;
+
                 var loggerFactory = s.GetRequiredService<ILoggerFactory>();
                 var activatorFactory = s.GetRequiredService<ActorActivatorFactory>();
                 var proxyFactory = s.GetRequiredService<IActorProxyFactory>();
@@ -54,6 +65,16 @@ public static void AddActors(this IServiceCollection services, Action<ActorRunti
             services.TryAddSingleton<IActorProxyFactory>(s =>
             {
                 var options = s.GetRequiredService<IOptions<ActorRuntimeOptions>>().Value;
+
+                //Replace the HttpEndpoint with an endpoint prioritizing IConfiguration
+                var configuration = s.GetService<IConfiguration>();
+                options.HttpEndpoint = options.HttpEndpoint != "http://127.0.0.1:3500"
+                    ? GetHttpEndpoint(configuration)
+                    : options.HttpEndpoint;
+                options.DaprApiToken = string.IsNullOrWhiteSpace(options.DaprApiToken)
+                    ? GetApiToken(configuration)
+                    : options.DaprApiToken;
+
                 var factory = new ActorProxyFactory() 
                 { 
                     DefaultOptions =
@@ -72,5 +93,88 @@ public static void AddActors(this IServiceCollection services, Action<ActorRunti
                 services.Configure<ActorRuntimeOptions>(configure);
             }
         }
+
+        /// <summary>
+        /// Retrieves the Dapr API token using a failover approach starting with an optional <see cref="IConfiguration"/>
+        /// instance, then trying to pull from the well-known environment variable name and then opting for an empty string
+        /// as a default value.
+        /// </summary>
+        /// <returns>The Dapr API token.</returns>
+        private static string GetApiToken(IConfiguration? configuration) => GetResourceValue(configuration, DaprDefaults.DaprApiTokenName);
+
+        /// <summary>
+        /// Builds the Dapr gRPC endpoint using the value from the IConfiguration, if available, then falling back
+        /// to the value in the environment variable(s) and finally otherwise using the default value (an empty string).
+        /// </summary>
+        /// <remarks>
+        /// Marked as internal for testing purposes.
+        /// </remarks>
+        /// <param name="configuration">An injected instance of the <see cref="IConfiguration"/>.</param>
+        /// <returns>The built gRPC endpoint.</returns>
+        private static string GetHttpEndpoint(IConfiguration? configuration)
+        {
+            //Prioritize pulling from IConfiguration with a fallback from pulling from the environment variable directly
+            var httpEndpoint = GetResourceValue(configuration, DaprDefaults.DaprHttpEndpointName);
+            var httpPort = GetResourceValue(configuration, DaprDefaults.DaprHttpPortName);
+            int? parsedGrpcPort = string.IsNullOrWhiteSpace(httpPort) ? null : int.Parse(httpPort);
+
+            var endpoint = BuildEndpoint(httpEndpoint, parsedGrpcPort);
+            return string.IsNullOrWhiteSpace(endpoint) ? $"http://localhost:{DaprDefaults.DefaultHttpPort}/" : endpoint;
+        }
+
+        /// <summary>
+        /// Retrieves the specified value prioritizing pulling it from <see cref="IConfiguration"/>, falling back
+        /// to an environment variable, and using an empty string as a default.
+        /// </summary>
+        /// <param name="configuration">An instance of an <see cref="IConfiguration"/>.</param>
+        /// <param name="name">The name of the value to retrieve.</param>
+        /// <returns>The value of the resource.</returns>
+        private static string GetResourceValue(IConfiguration? configuration, string name)
+        {
+            //Attempt to retrieve first from the configuration
+            var configurationValue = configuration?.GetValue<string?>(name);
+            if (configurationValue is not null)
+                return configurationValue;
+
+            //Fall back to the environment variable with the same name or default to an empty string
+            var envVar = Environment.GetEnvironmentVariable(name);
+            return envVar ?? string.Empty;
+        }
+
+        /// <summary>
+        /// Builds the endpoint provided an optional endpoint and optional port.
+        /// </summary>
+        /// <remarks>
+        /// Marked as internal for testing purposes.
+        /// </remarks>
+        /// <param name="endpoint">The endpoint.</param>
+        /// <param name="endpointPort">The port</param>
+        /// <returns>A constructed endpoint value.</returns>
+        internal static string BuildEndpoint(string? endpoint, int? endpointPort)
+        {
+            if (string.IsNullOrWhiteSpace(endpoint) && endpointPort is null)
+                return string.Empty;
+
+            var endpointBuilder = new UriBuilder();
+            if (!string.IsNullOrWhiteSpace(endpoint))
+            {
+                //Extract the scheme, host and port from the endpoint
+                var uri = new Uri(endpoint);
+                endpointBuilder.Scheme = uri.Scheme;
+                endpointBuilder.Host = uri.Host;
+                endpointBuilder.Port = uri.Port;
+
+                //Update the port if provided separately
+                if (endpointPort is not null)
+                    endpointBuilder.Port = (int)endpointPort;
+            }
+            else if (string.IsNullOrWhiteSpace(endpoint) && endpointPort is not null)
+            {
+                endpointBuilder.Host = "localhost";
+                endpointBuilder.Port = (int)endpointPort;
+            }
+
+            return endpointBuilder.ToString();
+        }
     }
 }